Many thousands of people use Ventoy and I haven't heard of anyone else with this problem, so it points to something about your method, your Ventoy USB drive or computer which is different from everyone else.
Unless you can give specific and accurate information it is difficult to find out where the problem is.
The next time it happens, perhaps you can provide more details?
Trying other multiboot loaders helps to narrow down the problem - for instance if you put the same ISO on the same USB drive and booted in the same way (UEFI or legacy) on the same PC but tested with Ventoy, E2B, E2B_agFM, and YUMI and they all failed - then it would look like some sort of USB hardware or BIOS driver fault. However, if only Ventoy gave the problem then it would look like a problem specific to Ventoy (E2B uses grub4dos, agFM uses grub2 and so does Ventoy).
If you used a USB 3 drive in a USB 3 port and got the problem, but then inserted a USB 2 extension cable and did not get the problem, then it would look like a USB I/O communication problem between that particular PC/USB port/USB drive.
We cannot solve a problem without information and we cannot reproduce the problem at the moment.
P.S. I did see a similar problem a few years ago and it was due to bad design of USB 3 ports which caused data corruption at high USB 3 speeds both under grub2\grub4dos (using the BIOS driver) and also under Windows 10 (using the Windows driver). I sent the brand new notebook back as being unfit for purpose! Bad USB 3 cables can also cause a similar issue.
Unless you can give specific and accurate information it is difficult to find out where the problem is.
The next time it happens, perhaps you can provide more details?
Trying other multiboot loaders helps to narrow down the problem - for instance if you put the same ISO on the same USB drive and booted in the same way (UEFI or legacy) on the same PC but tested with Ventoy, E2B, E2B_agFM, and YUMI and they all failed - then it would look like some sort of USB hardware or BIOS driver fault. However, if only Ventoy gave the problem then it would look like a problem specific to Ventoy (E2B uses grub4dos, agFM uses grub2 and so does Ventoy).
If you used a USB 3 drive in a USB 3 port and got the problem, but then inserted a USB 2 extension cable and did not get the problem, then it would look like a USB I/O communication problem between that particular PC/USB port/USB drive.
We cannot solve a problem without information and we cannot reproduce the problem at the moment.
P.S. I did see a similar problem a few years ago and it was due to bad design of USB 3 ports which caused data corruption at high USB 3 speeds both under grub2\grub4dos (using the BIOS driver) and also under Windows 10 (using the Windows driver). I sent the brand new notebook back as being unfit for purpose! Bad USB 3 cables can also cause a similar issue.